Plumbing Systems Commissioning
by Rebecca T. Ellis, P.E., LEED AP, CCP, CxA
November 1, 2008
This process offers benefits to the entire
project team, ranging from focused planning and improved communication, to
on-time successful completion and fewer callbacks.
Over the past century, and particularly over the
past 25 years, many facilities’ design innovations have been implemented in
order to enhance performance, protect occupant health and safety, reduce
operating costs, and minimize negative impact on the environment. These
innovations have led to increasingly complex — or, at least, unusual — building
systems. How does one know that all of the complex features are working and/or
are prepared to work when called upon after construction is complete?
Traditional design and construction industry processes have not kept pace with
the evolving systems the industry is expected to deliver. Business-as-usual has
been focused on equipment — its selection and sizing (design), and its
installation and startup (construction) – with little or no attention being
paid to how the individual pieces of equipment function together as systems.
It is no longer the case that, just because every component is installed and
energized, you have a properly functioning building system. The introduction of
computerized controls and networked communication between components has
resulted in a critical system element, which cannot be observed through a
traditional site observation or punchlist process.
Building systems commissioning is a process that has been developed to
integrate into and fill this void in the traditional design and construction
process. Commissioning is a systematic process of ensuring that building
systems are designed, installed, integrated, and tested to perform according to
the design intent and the building owner’s operational needs. It is a process
that enhances the quality assurance of a building project and requires an
extended project team effort to realize the full benefits.
What is Commissioning?
|
|
| Figure 1. Design-Phase Commissioning Activities |
|
Commissioning begins with the development of a
project-specific Commissioning Plan. The Commissioning Plan is the roadmap for
the commissioning process through pre-design, design, construction and
occupancy of the facility. It lays out the roles and responsibilities for each
team member during the various phases of the project, identifies the systems to
be commissioned, and defines the level of rigor for each system. It establishes
expectations early so there are no surprises later in the project for any team
member.
The commissioning process is facilitated by a Commissioning Professional (also
known as a Commissioning Authority or Commissioning Agent). However,
commissioning is a team sport and a primary role of the Commissioning
Professional is that of a coach. The team is comprehensive and includes the
owner’s project and operations staff, the design team and construction
team.
Very simply, commissioning helps the project team understand the owner’s performance
goals and is a step-by-step process for successfully achieving and verifying
those goals at the end of construction and prior to owner occupancy. The
following are some of the fundamental elements of commissioning in project
chronological order:
- Prepare Commissioning Plan;
- Define owner’s systems performance acceptance criteria;
- Review design documents for compliance with acceptance
criteria;
- Prepare commissioning specification section for bidding documents;
- Review shop drawings and equipment submittals for compliance with
acceptance criteria;
- Observe installation for future maintenance and operations
accessibility issues;
- Verify that equipment is installed and started per manufacturer’s
recommendations;
- Provide appropriate time in the construction schedule for
coordinating and executing “system” level activities such as air and water
testing and balancing, controls programming and checkout, and inter-system
communications;
- Verify functional performance of the systems and integrated systems
to confirm final compliance with the acceptance criteria;
- Train owner’s staff in equipment maintenance and systems
operation;
- Provide system-level operations documentation for future reference
and training of owner’s staff; and
- Develop Re-Commissioning and/or On-Going Commissioning plans for the
owner’s execution throughout the life of the facility.
A Necessary Step Further
Commissioning does not replace the quality
control component of a project but rather enhances the quality process on the
jobsite. Quality control focuses on the static elements of the project, e.g.,
equipment, piping, conduit, installation coordination, etc. Commissioning goes
a necessary step further to focus on how all of the static elements dynamically
work together as systems. It is only through the interaction of system elements
that the owner’s performance requirements can be met.
The Commissioning Professional is the eyes and ears of the future operations
staff during the design and construction process, and the commissioning process
brings the long-term view of the facility to the forefront of all decisions.
When there are decisions to be made with respect to budget, schedule, and
quality, the commissioning process helps bring as much weight to the quality
issues as is given to the other two goals. Quality will not always “win,” but
the owner will be able to make informed decisions with an understanding of the
long-range cost of each decision.
To close the loop on the process it is essential that facilities engineering
staff responsible for operating the systems are adequately prepared through
training, documentation, and involvement in the commissioning process. Although
the traditional project closeout activities include training of the owner’s
staff, that training is typically limited to the preventive maintenance and
troubleshooting of individual pieces of equipment. Commissioning takes this
further by focusing on systems operation training.
Systems training provides explanations of the system performance criteria and
how the designers’ systems will achieve those criteria. The goal of this
training is to convey how all of the individual pieces of equipment are
uniquely configured to operate as a “system.” There is heavy emphasis on
schematic diagrams and automatic and manual control sequences. And, in the
interest of sustained proper operation of the equipment and systems, commissioning
heavily emphasizes the importance of complete, accurate, and easy-to-use
systems documentation, designed with the future operations staff in mind.
What Systems Should be Commissioned?
|
|
| Figure 2. Early-Construction-Phase Commissioning Activities |
|
Any system whose performance can be defined in
measurable terms can be included in the commissioning process. The following
questions are helpful for determining strong candidates for commissioning on
specific projects:
1. Where have problems consistently occurred on past projects?
2. What are the risks of system malfunction after occupancy/beneficial
use?
3. What are the political implications of poor system performance?
4. How easily would deficiencies be found without commissioning?
5. How many parties are involved in design and construction of a single
system?
For the past 15-20 years, heating, ventilating, and air conditioning (HVAC)
systems have been facility owners’ first choice for commissioning. This is
because HVAC systems have historically been the source of most building
problems. In turn, I believe this is because HVAC systems require so many
different subcontractors for successful operation (sheetmetal, piping,
electrical, insulation, controls, test and balance, etc.). This number of
responsible parties results in complex coordination during construction and
also results in challenging troubleshooting if things don’t operate correctly
upon system start-up.
Plumbing Systems Commissioning - History
So, where do plumbing systems fit in? Until
recently, plumbing systems were rarely selected for the rigors of the
commissioning process. That is because most traditional plumbing systems don’t
score high on the previously noted five-question criteria
test:
1. Where have problems consistently occurred on past projects?
Sure, there have been plumbing system failures and/or malfunctions in
new buildings, but the plumbing systems are not what keep owners up at night
worrying about whether or not they will function when a project is complete.
2. What are the risks of system malfunction after occupancy/beneficial
use?
Probably the biggest plumbing system risk in a new building is a pipe
failure or leak that could cause serious collateral damage to the building.
Again, this has occurred in the past, but it is not common. Because it is such
a big risk, the traditional project delivery process includes pressure testing
all piping; and that, for the most part, helps to mitigate most potential
problems.
3. What are the political implications of poor system performance?
This is a criterion that may qualify typical plumbing systems for
commissioning in some building types. For example, in a public sports arena,
what would be the result of a systemic problem with toilet operation? In a
private fitness center, what would be the result of a lack of hot water or
timely hot water delivery?
4. How easily would deficiencies be found without commissioning?
Other than an insidious hidden leak, most plumbing system deficiencies
become evident very quickly as people find automatic faucets and flushes that
don’t work; low water pressure; insufficient hot water; etc. A building owner
does not need to pay a professional to search out and find these types of
deficiencies.
5. How many parties are involved in design and construction of a single
system?
With the exception of a few electrical connections, plumbing systems
have historically been the responsibility of a single subcontractor. If there
are problems with plumbing, there has not been much discussion about who is
responsible for correcting them.
The above questions historically resulted in building owners choosing to
commission only the following plumbing systems, if they chose to commission
plumbing at all:
Domestic water heaters and recirculation pumps;
Sump pumps; and
Sewage ejector pumps.
Plumbing Systems Commissioning — Today
|
|
| Figure 3. Testing-and-Training Commissioning Activities |
|
All of this has changed since the turn of the
millennium. Today even plumbing systems are getting to the integrated building
system action and are taking on complexities previously unknown. Most of the
new plumbing system designs are a result of the desire for sustainable
buildings, particularly with respect to water conservation, waste water
reduction, and energy/carbon footprint savings.
The United States Green Building Council’s Leadership in Energy and
Environmental Design (LEED) program requires that a building’s domestic hot
water system(s) be commissioned as a prerequisite for certification. The LEED
rating system has also been directly responsible for many of the innovative
plumbing systems currently being designed and installed in buildings. These
include, but are not limited to:
- Rain water collection and use for flushing toilets,
irrigation, and other non-potable applications;
- Gray water collection for flushing toilets, irrigation, and other
non-potable applications;
- Solar water domestic water heating;
- Waste energy recovery for domestic water preheat; e.g., transferring
heat from chiller condensers, boiler blow-down, boiler exhaust stacks, etc.;
- Irrigation system flow and pressure monitors;
- Sub-metering water consumption;
- Time-of-day scheduling of domestic water distribution; and
- Composting toilets.
Each of the above systems, partially because of their unique nature and
partially because of their inherent controls complexity, are excellent
candidates for the commissioning process.
Summary
Commissioning offers a substantial benefit to
the design and construction project by providing a framework in which the
entire project team can successfully achieve their operational, schedule, and
budget goals. However, the greatest value from commissioning accrues to the
facility owner through focused planning, documentation, and training for the
on-going operation and maintenance of the new systems.
The project team benefits from improved communication and coordination, on-time
successful completion and turnover of the building to the owner, and far fewer
callbacks after project completion. The owner receives a building that works at
the time of occupancy, while the designers and contractors have a satisfied
customer and a more profitable project.
The owner’s facilities team takes over a building that they understand and in
which they have confidence. They are also given the tools to successfully serve
their customers – the building occupants.
|